COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 3639 Konkoly Observatory Budapest 17 July 1991 HU ISSN 0374 - 0676 A CONTINUATION OF PHOTOELECTRIC PHOTOMETRY OF RHO CASSIOPEIAE This paper represents a continuation of previous photoelectric observations of the variable star rho Cassiopeiae (Leiker et al., 1990, 1989, 1988, 1987). Rho Cassiopeiae (rho Cas, HR 9045, HD 224014, SAO 035879) is a supergiant (F8pIA) star (Percy & Keith, 1985). It was discovered to be a variable in 1900 by Louise D. Wells (Pickering, 1901). Much of the time this star was confined to a brightness between 4.1m and 5.1m (Bailey, 1978). However, between August 1945 and June 1947 rho Cas decreased in brightness more than a magnitude (Gaposchkin, 1949). After it recovered from this minimum, rho Cas continued its irregular variation in brightness between 4.1m and 5.1m. Rho Cas was observed by Leiker, Hoff, and Caruso at Oak Ridge Observatory, Harvard, MA from September 1990 through February 1991. A 0.4 meter Cassegrain telescope and a STARLIGHT-1 photon counting photometer with standard B and V filters was used. This is the same photometer that was used in our previous work. HR 9010 (HD 223173, SAO 35761, K3 II, V = 5.51 m, B-V =1.65) was used as the comparison star. These delta magnitudes are not corrected for color or extinction. Standard deviation (sigma) was calculated in the usual manner from three delta magnitudes. Table I lists the Delta V and Delta B magnitudes. Figures 1 and 2 are graphical representations of the data presented in Table I. Table I. delta V and delta B magnitudes of rho Cas obtained by Leiker, Hoff, and Caruso HJD Delta Vm sigma HJD Delta Bm sigma 2448107.7 -1.001 0.049 2448107.73 -1.416 0.004 2448116.6 -0.989 0.027 2448116.6 -1.441 0.010 2448130.6 -1.044 0.002 2448130.65 -1.458 0.001 2448138.6 -1.060 0.049 2448138.6 -1.455 0.020 2448145.6 -1.055 0.024 2448145.6 -1.481 0.011 2448153.54 -1.055 0.014 2448153.56 -1.466 0.009 2448155.52 -1.060 0.014 2448155.54 -1.487 0.017 2448159.58 -1.048 0.016 2448159.59 -1.464 0.006 2448166.61 -1.019 0.021 2448166.63 -1.428 0.006 2448169.7 -1.021 0.007 2448169.72 -1.396 0.011 2448180.72 -1.046 0.003 2448180.73 -1.447 0.002 2448189.49 -1.029 0.009 2448189.51 -1.427 0.009 2448192.6 -1.008 0.014 2448192.61 -1.419 0.001 2448196.52 -1.011 0.002 2448196.53 -1.418 0.004 2448200.66 -0.992 0.009 2448200.67 -1.398 0.011 2448204.65 -1.020 0.001 2448204.67 -1.423 0.004 2448211.76 -1.029 0.007 2448215.66 -0.986 0.024 2448226.56 -1.021 0.011 2448226.58 -1.397 0.019 2448285.47 -0.961 0.018 2448285.5 -1.341 0.007 2448289.51 -0.979 0.004 2448289.52 -1.309 0.002 2448300.48 -1.000 0.009 [FIGURE 1] Figure 1. DeltaV magnitudes of rho Cas obtained by Leiker, Hoff, and Caruso [FIGURE 2] Figure 2. DeltaB magnitudes of rho Cas obtained by Leiker, Hoff, and Caruso The authors wish to acknowledge the Smithsonian Astrophysical Observatory and Dr. Robert P. Stefanik for the use of the 0.4-M telescope at the Oak Ridge Observatory, Harvard, MA. They would also like to thank Dr. Thomas A. Hockey and the University of Northern Iowa for the use of a photoelectric photometer. P. STEVEN LEIKER DARREL B. HOFF Harvard-Smithsonian Center for Astrophysics 60 Garden Street Cambridge, MA 02138 USA JOSEPH R. CARUSO Oak Ridge Observatory Harvard, MA 01451 USA References: Bailey, J.: 1978, Journal of the British Astron. Association 88, (4), 397-401. [BIBCODE 1978JBAA...88..397B ] Gaposchkin, S.: 1949, Harvard College Obs. Bull. No. 919,18-19. [BIBCODE 1949BHarO.919...18G ] Leiker, P. S., & Hoff, D. B.: 1990, IBVS No. 3490. Leiker, P. S., Hoff, D. B., & Milton, R.: 1989, IBVS No. 3345. Leiker, P. S., Hoff, D. B., Nesbella, J., Gainer, M., Milton, R., & Pray, D.: 1988, IBVS No. 3490. Leiker, P. S., & Hoff, D. B.: 1987, IBVS No. 3020. Percy, J. R., & Keith, D. W.: 1985, Cepheids: Theory and Observations. (ed. B. F. Madore), University of Cambridge Press, pp. 89-90. Pickering, E. C.: 1901, Harvard College Obs. Circular. No. 54. [BIBCODE 1901HarCi..54....1P ]